Wall lining for steam generators



Feb. 1, 1966 B. GFRERER WALL LINING FOR STEAM GENERATORS 4 Sheets-Sheet 1 Filed NOV. 29, 1962 INVENTOR. BRUNO GFIPfRE Q ATTORNEY Feb. 1, 1966 B. GFRERER WALL LINING FOR STEAM GENERATORS 4 Sheets-Sheet 2 Filed Nov. 29, 1962 INVENTOR. BRUNO GF/PERER ATTORNEY Feb. 1, 1966 B. GFRERER WALL LINING FOR STEAM GENERATORS 4 Sheets-Sheet 5 Filed NOV. 29, 1962 IN VEN TOR. Bea/v0 GIFPERER ATTORNEY Feb. 1, 1966 B. GFRERER 3,232,232

WALL LINING FOR STEAM GENERATORS Filed Nov. 29, 1962 4 Sheets-Sheet 4 9 6 INVEN TOR.

Bea/v0 GFREEER A T TORNE Y United States Patent Ofifice 3,232,282 Patented Feb. 1, 1965 3,232,282 WALL lLlNlNG FOR STEAM GENERATORS Bruno Gfrerer, Winterthur, Switzerland, assignor to Sulzer Freres, S.A., Winterthur, Switzerland, in corporation of Switzerland Filed Nov. 29, 1962, er. No. 240,923 filairns priority, application Switzerland, Dec. 1, 1961, 14,!lti3/ 61 9 Claims. ((11. 122-510) The present invention relates to a lining for the walls of a steam generator, the lining being composed of a plurality of hollow, platelike elements conducting a heat absorbing fluid, the elements being edgewise juxtaposed with a space therebetween to permit relative expansion.

Boiler wall linings, for example, made of parallel, longitudinally adjacent tubes forming a ribbon which is bent in its plane in meanderlike fashion whereby all tubes are in the same plane, are known to be support-ed in such manner that relative expansion due to temperature changes as occur between regular operation of the boiler and standstill, can take place without unduly increased tension and stress of the material of which the linings are made. This is accomplished by bending the tubes at least once between two locations where the tubes are fixed to a stationary part. The tubes are usually guided between said locations to move in the plane of the lining upon heat expansion and contraction. The Width of the ribbons formed of parallel adjacent tubes depends on the temperature of the tubes. A meander-shaped ribbon made of parallel, longitudinally adjacent tubes which has oblong horizontal portions has horizontal oblong spaces between neighboring portions of marginal tubes of the ribbon for permitting heat expansion of the tubular ribbon transversely to the longitudinal axis. It is customary to provide the neighboring portions of marginal tubes of the horizontal portions of the ribbon with fins to close the horizontal spaces. If the tubular ribbon lines the walls of a combustion chamber, the wall portions adjacent to the aforesaid spaces are protected by said fins against radiation. If the tubular ribbons consist of a great number of parallel tubes the spaces between marginal tubes of parallel portions of the ribbon must be rather wide to permit transverse heat expansion of the wide ribbon. Corre spondingly wide fins must be used to bridge the wide clearances between oblong portions. These wide fins are likely to become overheated. If the space between neighboring portions of a marginal tube of the tubular ribbon is narrow this tube has 180 bends of small radius at the end of the oblong portions of the meander-shaped ribbon. This small radius is undesirable.

It is an object of the present invention to provide a wall lining for shielding the inside of a Wall of a steam generator, particularly of the combustion chamber thereof, against heat radiation which lining can freely expand and contract at changing temperature. The wall lining according to the invention is formed by platelike elements forming a continuous ribbon and including conduits conducting a heat absorbing fluid longitudinally of the ribbon. The latter may have the shape of a meander whereby all platelike elements are placed in the same plane and a slotlike clearance or space is provided between neighboring marginal portions of the ribbon for permitting heat expansion and contraction of the ribbon. This clearance is preferably wider than the clearance needed for allowing temperature expansion and contraction in the direction normal to the longitudinal axis of the ribbon. At least one tube conducting a heat absorbing fluid is placed in this widened clearance and is spaced at preferably substantially equal distances from the neighboring edges of the platelike elements.

With the aforedescribed arrangement fins of undesired great width for bridging the space between the neighboring edges of the Platelike elements are avoided. The 180 hairpin bends of the marginal pipe of a meander-shaped ribbon formed of a plurality of longitudinally adjacent pipes can have a much greater radius than is possible with a meander-shaped ribbon having only a narrow space between neighboring edge portions of the ribbon. The parts of the wall of the steam generator behind the widened spaces are shielded against heat radiation by the tube or tubes placed in the spaces.

The platelike elements of the wall lining according to the invention may be provided with a plurality of parallel channels for conducting a heat absorbing fluid. The platelike elements may be formed by a plurality of parallel pipes. The wall lining may be in the form of a ribbon composed of a plurality of longitudinally adjacent parallel pipes and bent in meanderlike fashion. If there is more than one meander-shaped tubular ribbon on a boiler wall a space may be provided between said ribbons and a tube conducting a heat absorbing fluid may be placed in said space.

Fins may be connected to the tubes longitudinally thereof which tubes are placed either in oblong spaces between turns of the same meanderlike tubular ribbon or in spaces between two different tubular ribbons. In lieu of connecting fins to and longitudinally of the tubes placed in the spaces between neighboring portions of a meanderlike heat absorbing ribbon or between two such ribbons, the fins may be connected to the edges of neighboring portions of the ribbon or ribbons. If desired fins may be provided on the neighboring edges or marginal pipes of heat conducting ribbons as well as on the tubes placed between said neighboring edges or marginal pipes. In this case the fins on the intermediate tube may partly overlay the fins on the ribbons if the intermediate pipe conducts a cooler fluid than the ribbons. If the ribbons conduct the cooler fluid, the fins thereon preferably overlay the fins on the intermediate tube. The fins may be utilized to guide the movements of the parts provided with fins relative to each other upon heat expansion and contraction.

The intermediate tube or tubes may be connected for fluid fiow to the pipes or channels in the meanderlike ribbons. The fluid in the intermediate tubes may be cooler or flow at a greater velocity than the mediumconducted by the adjacent ribbon in order to increase the cooling efiect of the intermediate tubes.

If the ribbon is in the shape of a meander it has hairpin bends which have a small radius and extend through 180 on the inside and which are bent twice through in the outside. In cold condition of the wall lining the clearances between the parallel oblong portions of the meander-shaped ribbon are preferably relatively narrow in the neighborhood of the inside of the bends and are relatively wide in the neighborhood of the outside of the bends because, there, the heat expansionand contraction amounts to about twice the heat expansion and contraction in the neighborhood of the inside of the bends.

If the aforementioned fins are used for guiding the respective parts to move in the general plane of the lining, the guide fins may be made shorter in the neighborhood of the inside of the bends than in the neighborhood of the outside of the bends. This reduces the thermal loadon the fins.

Two symmetric tube systems may be provided for lining wall portions of the combustion chamber of a steam generator. Each tube system may be formed by a ribbon conducting a cooling fluid and in the shape of a meander whereby oblong portions of the ribbon and the oblong spaces between neighboring oblong portions are horizontal. Every other of said spaces of one tube system is in line and communicates with a corresponding space of the second tube system. An intermediate tube placed in the space of one tube system preferably extends into and also forms the intermediate tube in the corresponding communicating space of the second tube system. There is a plurality of horizontal spaces in this system and the intermediate tubes in every other of said spaces are preferably connected for fluid fiow with the ribbon of one system and the intermediate tubes in the balance of said spaces are preferably connected for fluid flow with the ribbon forming the second system. It may be of advantage to provide a common inlet header and a common outlet header for both systems. In that case the intermediate tubes of both tube systems may be interposed for fiuid flow between said headers.

The novel features which are considered characteristic of the invention are set forth with particularity in the apended claims. The invention itself, however, and additional objects and advantages thereof will best be understood from the following description of embodiments thereof when read in connection with the accompanying drawing wherein:

FIG. 1 is a schematic perspective illustration of a wall lining according to the invention for two vertical walls, placed at a right angle, of the combustion chamber of a steam generator.

FIG. 2 is a vertical sectional view showing structural details of a lining according to the invention; the section shown in FIG. 3 is made along line IIII of FIG. 1.

FIG. 3 is a part-sectional perspective schematic illustration of four tubular systems according to the invention, lining the walls of a combustion chamber having a rectangular cross section.

FIG. 4 is a schematic illustration of adjacent parts of two different tube systems forming linings for a wall of a steam generator.

FIG. 5 is a cross-sectional view of two modified platelike elements of a wall lining according to the invention, the figure also showing a section of a tube placed in a space between the sections.

FIG. 6 is a diagrammatic illustration of a detail of the structure according to the invention.

Referring more particularly to FIGS. 1 and 2 of the drawing, numeral 4 designates a ribbon conducting a heat absorbing fluid. The ribbon may be made up of a plurality of longitudinally juxtaposed pipes, as shown in FIG. 2. The ribbon is in the shape of a meander having relatively long superposed horizontal portions and short vertical portions interconnecting the horizontal portions. The horizontal portions, of which only four, numbered 5, 6, 7 and 8 are shown, are bent at a right angle along a line 33 to fit into a corner of a combustion chamber having walls indicated by numerals 1 and 2. Numeral 11 designates a tube having portions schematically represented by a single line and placed in each space 9 between two horizontal oblong neighboring portions of the tubular ribbon and having portions represented by dotted lines and placed in the rear of the ribbon 4, i.e. between the ribbon and the walls lined thereby.

The individual pipes or elements forming the ribbon 4 are fixed in space at the locations 1212, 1313, 14 14 and 1515. Dotted lines 19 designate vertical supports on which the ribbon is guided to move vertically parallel to the wall which it lines. The supports 19 may be in the form of tubes whose temperature is lower than that of the wall lining. Alternatively, the supports may be formed by girders or columns anchored in the wall which is lined by the ribbon 4. The vertical portions of the meanderlike ribbon which are fixed at the locations 12-42, 1313, 1414 and 15-45 expand and contract at varying temperature in the direction of the arrows 16. When cold, the portion of the lower marginal part of the horizontal ribbon portion 8 between locations 17 and 18 is at a higher elevation than when the ribbon is hot. The upper marginal part of the ribbon portion 7 is at a lower elevation than when the ribbon is hot. In order to provide space for the movement of the neigh- 4. boring marginal parts of the ribbon a space or slot 9 is provided therebetween. If this space has equal width throughout its length when the system is hot, the space is greater at the location 17 than at the location 20 when the system is cold. In FIG. 6 a marginal pipe 22 of a cold ribbon is shown in solid lines and the same marginal pipe of a hot ribbon is shown in dash-dot lines. FIG. 6 also shows that the lateral extension of the fins 28 may be made smaller adjacent to the 180 bend of the pipe 22 than at the 90 bends of the pipe 22. The position of the intermediate tube 11 placed in the space 9 is not fixed in the neighborhood of the location where the ribbon 4 is fixed. The tube 11 is either fixed or guided on the supports 19 at the location 21. The tube 11 is so supported that its distances from the neighboring marginal portions of the oblong parts of the ribbon between which the tube is located remain about equal at varying temperatures, i.e. the tube remains in the middle of the space between the horizontal oblong ribbon portions.

FIG. 2 shows the position of pipes forming the meanderlike ribbon at the location 11-11 of FIG. 1 when the system is cold. The pipes 22 form part of the ribbon portion '7 and the pipes 22 form part of the ribbon portion 8. At rising temperature the pipes 22 move in the direction of the arrow 30' and the pipes 22 move in the direction of the arrow 30. The intermediate tube 11 is placed between the lower marginal pipe 22' of the ribbon portion 8 and the upper marginal pipe 22 of the ribbon portion 7. The tube 11 does not move laterally upon temperature changes.

Pins 28 are welded to the tube 11 in vertical diametrically opposed position. Fins 27 are welded to the bottom of the lowermost pipe 22 of the ribbon portion 8 and to the top of the uppermost pipe 22 of the ribbon 7. Laterally spaced from the fins 27 guide members 29 are welded to the aforesaid marginal pipes 22' and 22. The fins 28 slidably extend between the fins 27 and the guide members 29.

If the intermediate tube 11 is more effectively cooled by increasing the flow velocity of the fluid therethrough and/ or by conducting a relatively cool fluid therethrough, the fins 28 may be placed in front of the fins 27 so that they are more exposed to radiant heat than the fins 27. The guide members 29 may then be welded to the tube 11 instead of to the pipes 22 and 22' and the fins 27 may extend between the fins 28 and the guide members 29.

The fins 27 and 28 and the intermediate tube 11 shield the portions of the wall, for example, of the combustion chamber of a steam generator, which portions are behind the spaces between the neighboring portions of the marginal pipes of the ribbon 4. The shielded wall includes heat insulation 32 covered by sheet metal 31 which is directly behind the carrier tubes 19.

A flap 24 welded to the tube 11 has a recess 33 receiving a pin 23 which is fast on a support tube 19. The tube 11 is thereby held in a plane parallel to the plane of the wall which is shielded by the structure according to the invention. The tube 11 is free to expand longitudinally. Parts neighboring the tube 11 are held in the aforesaid plane by the fins 27, 28 and the guide members 29. Every other of the pipes 22 and 22' is provided with flaps 24 provided with recesses 33 for receiving pins 23 which are fast on the support tube 19. This structure permits movement of the pipes 22 and 22 in the direction of the arrows 30 and 30, respectively, but does not permit movement of the pipes in a direction normal to the plane of the wall of the steam generator. The pipes 22 which are beneath the pipe 22 facing the tube 11., are provided with rods 26 which are welded to the respective pipes 22 longitudinally thereof and which are so placed as to prevent lateral movement of the pipe 22 which is not connected to the tube 19. Similarly, the pipes 22' which are next to the tube 11 are provided with rods 26' for guiding the pipe 22' which is not supported by the support or carrier tube 19.

FIG. 3 is a perspective illustration of a system for shielding the walls of a combustion chamber of a steam generator by means of pipes conducting a heat absorbing fluid and arranged according to the invention. FIG. 3 shows only the pipes shielding the rear wall and pipes shielding a part of the lateral walls of the combustion chamber. A plurality of parallel juxtaposed pipes forms each of tubular ribbons 34, 35, 36 and 37 which are bent in meanderlike fashion. Each tubular ribbon shields a portion of a wall of the combustion chamber and a portion of a wall of the combustion chamber placed at a right angle to the first wall. The pipes forming the ribbons 35 and 36 are connected to a distributor or inlet header 38 into which a heat absorbing fluid is fed (arrow 39). The pipes of the ribbons 35 and 36 terminate in a common outlet header or collector 40 and form a first tube system from which the heated fluid flows in the direction of the arrow 41. The pipes of the ribbons 34 and 37 receive heat absorbing fluid from a distributor or inlet header 42 into which heat absorbing fluid is fed (arrow 43). The pipes of the ribbons 34 and 37 terminate in a common collector or outlet header, not shown and form a second tube system. The ribbons 34, 35 are arranged symmetrically with respect to the ribbons 36 and 37. The pipes forming the ribbons 34 to 37 have relatively long horizontal portions and relatively short vertical portions interposed between the horizontal portions. The neighboring oblong portions of the ribbons are spaced from one another, the ribbon 35 forming spaces 44 and 45 and the ribbon 36 forming spaces 44 and 45". The neighboring edges of the relatively long horizontal portions of the ribbon 34 are spaced and form oblong horizontal spaces 45'. The spaces 45' of the ribbon 34 which are on the same level as the spaces 45 of the ribbon 35 communicate with one another. The same is the case of the spaces 44 of the ribbon 35 and 44 of the ribbon 36. Each ribbon has two marginal pipes, the marginal pipes of the ribbon 37 being numbered 37' and 37" and the marginal pipes of the ribbon 34 being numbered 34' and 34. The marginal pipes of the ribbon 35 are numbered 35 and 35". The marginal pipes of the ribbon 36 are not particularly illustrated. The marginal pipes have oppositely placed, parallel, spaced, neighboring portions forming a space therebetween. The neighboring portions of the marginal pipe 35 forming the spaces 44 are fully illustrated and designated by numerals S0 and 81. A first tube 50 has portions 82 placed in spaces 45 between neighboring portions of marginal pipes of the ribbon 36. The tube portions 82 also extend into spaces 83 between neighboring portions of the marginal pipe 37" of a second ribbon 37. A second tube 47 has portions placed in second spaces 44 between neighboring marginal pipe portions of the ribbon 36 and also extending into spaces 44 between neighboring marginal pipe portions of the ribbon 35. v

The tube 47 connected to the distributor 38 has a horizontal portion placed in the middle of the communicating lowermost spaces 44 and 44 of the ribbons 35 and 36. The tube 47 continues into the third, counted from the bottom, horizontal communicating spaces 44 and 44 of tie ribbons 35 and 36 and thereupon continues into the collector 40. The parts of the tube 47 which are not coextensive with the spaces 44, 44 are placed behind the ribbons 36, 3'7 and 35, as shown by dotted lines. The part 47 of the tube 47 which is placed behind the rib bons 36 and 37 is bent to form an angle permitting heat expansion and contraction. The tube 47 is rigidly supported at the locations designated by numerals 56 and 57 by conventional means, not shown. A tube 48 is connected to the distributor 38 and has a first portion placed behind the ribbon 35 which first portion continues in a horizontal portion placed in the communicating spaces 44, 44 of the second meanders from the bottom of the ribbons 35 and 36. The tube 48 continues then into a bent tube portion 48' which is placed behind the ribbons 36 and 37 and which continues into a horizontal portion placed in the communicating spaces 44 and 44 of the top meanders of the ribbons 35 and 36. The tube 48 continues in a portion behind the ribbon 35 and connected to the collector'40. Tubes 49 and 59 are similarly arranged in combination with the ribbons 36 and 37 as are the tubes 47 and 48 in combination with the ribbons 35 and 36. The tubes 47 to 59 form part of the first tube system and the tubes 51 to 53 form part of the second tube system.

Tubes 51 and 52 are connected to the header 42 and are arranged to form intermediate tubes in the ribbons 37 and 34 and tubes 53 and 54, also connected to the header 42, are arranged to form intermediate tubes in the ribbons 34 and 35 in a manner similar to the arrangement of the tubes 47 to 50 in combination with the ribbons 35, 36 and 37.

The invention is not limited to the particular relative arrangements of the ribbons and intermediate tubes shown in FIG. 3. For claritys sake, the tubes 47 to 54 are shown in FIG. 3 to be of smaller diameter than the pipes forming the tubular ribbons. In most practical cases the diameter of the tubes forming intermediate tubes in the spaces between neighboring parts of meander-shaped tubular ribbons have the same diameter as the neighboring pipes of the ribbons. The length of the tubes forming the intermediate tubes must be so arranged relative to the length of the pipes forming the ribbons that a desired relative flow rate through the tubes and through the ribbons is obtained.

In the arrangement shown in FIG. 4 tubular ribbons 61 having relatively long horizontal portions and relatively short vertical portions and ribbons having relatively long vertical portions and relatively short horizontal portions are placed within the same chamber for shielding the walls thereof. The two ribbon systems may be separated by a space 62 within which an intermediate tube 63 is placed. The pipes forming the ribbon 66 are fixed in space at the locations indicated by crosses 64. The pipes of the ribbon 61 are fixed in space at the location indicated by crosses 65. If the distances 66 and 67 between the locations 65 and the tube 63 and between the tube 63 and the locations 64 are equal and if the ribbons are thermally about equally loaded, the tube 63 is placed in the center of the space 62. The tube 63 is fixed in space approximately at the location 68. With this arrangement the neighboring portions of the ribbons 60 and 61 expand about equally and the tube 63 remains in the center of the space 62. If the portion 61' of the ribbon 61 is thermally higher loaded than the portion 60 of the ribbon 60, the distance 66 is preferably made smaller than the distance 67 so that the edges of the ribbons facing the tube 63 move about equally when their temperature is reduced as it is the case when operation of the steam generator is interrupted and When it is increased during normal operation of the steam generator. In other words, the distances between an intermediate tube and the means connecting one ribbon or platelike element conducting heat absorbing fluid adjacent to said tube to support means and between the intermediate tube and the means connecting a second ribbon adjacent to said tube to the support means are inversely proportional to the thermal load on the respective ribbons.

If the thermal load on the portion 61 of the ribbon 61 is considerably higher than that on the portion 60 of the ribbon 60, the distance 66 may be still more reduced. In that case the movement of the ribbon 61 to and from the tube 63 is smaller than the movement of the ribbon 60 to and from the tube 63. In this case fins, not shown, connected to the tube 63 at the side facing the ribbon 61 may be made less wide than the fins on the side of the tube 63 facing the ribbon 60. In this way the thermal load on the fins can be suitably controlled which is important if the fins are thermally loaded to the uppermost limit.

If the wall lining comprises a meanderlike ribbon 60 and return bend tubes 70 placed in the relative position shown in FIG. 4, a tube 63 may be interposed between the return bends of the tubes 70 and the edge of the ribbon faced by the return bends.

FIG. shows an embodiment of the invention wherein the platelike elements 72 lining the inside wall of a steam generator are formed of juxtaposed sheets having opposed corrugations 72 and 72" forming tubular cavities '75 for conducting a heat absorbing fluid. The two sheets are welded together at the locations 76 between the corrugations. An intermediate tube 74 is placed in the space 73 between neighboring edges of two platelike elements 72.

I claim:

1. A lining for a wall of a steam generator, comprising:

at least one plane ribbon formed by a plurality of parallel and adjacent pipes conducting a heat absorbing fluid,

said ribbon being bent 180 a plurality of times in the plane of the ribbon and having marginal pipes having spaced, parallel and oppositely placed portions permitting heat expansion and contraction of said ribbon in the direction normal to the longitudinal extension thereof,

a continuous tube conducting a heat absorbing fluid, said tube extending consecutively through a plurality of the spaces between said oppositely placed pipe portions and in substantially parallel relation to said pipe portions,

support means placed laterally of said ribbon and of said tube, and

separate means individually and independently connecting said ribbons and said tube to said support means.

2. A lining for a wall of a steam generator as defined in claim 1 wherein said tube is connected for fluid flow to said pipes forming said ribbon.

3. A lining for a wall of a steam generator as defined in claim 1 wherein the marginal pipes of said ribbon are consecutively bent through 90, through 180 and again through 90, the space between opposed portions of said marginal pipes adjacent to the 180 bend being smaller than the space between opposed portions of said marginal pipes adjacent to the 90 bends, when said ribbon is cold.

4. A lining for a wall of a steam generator as defined in claim 1 wherein the marginal pipes of said ribbon are consecutively bent through 90, through 180 and again through 90, and said tube portions placed in the spaces between said oppositely placed pipe portions are provided with fins extending laterally in opposite directions from said tube portions, the lateral extension of said fins adjacent to said 180 bends being smaller than the lateral extension of said fins adjacent to the 90 bends.

5. A lining for a wall of a steam generator, comprising:

at least two ribbons, each ribbon being composed of a plurality of parallel and adjacent pipes conducting a heat absorbing fluid,

said ribbons having edgewise and pairwise juxtaposed portions with spaces therebetween to permit heat expansion and contraction of the juxtaposed ribbons,

a continuous tube conducting a heat absorbing fluid, said tube having portions individually placed in said spaces between the juxtaposed portions of said ribbons and extending consecutively through said spaces,

support means placed on one side of said ribbons and laterally of said tube portions, and

means individually and independently connecting said ribbons and said tube portions to said support means for fixing the relative position of said ribbons and of said tube portions.

6. A lining for the walls of a steam generator, comprisa plurality of tubular ribbons,

each ribbon including a plurality of longitudinally juxtaposed pipes conducting a heat absorbing fluid,

each of said ribbons being bent 180 and having marginal pipes having spaced, parallel, neighboring portions forming spaces therebetween,

a first tube conducting a heat absorbing fluid and having portions individually placed in spaces formed between neighboring marginal pipe portions of a first ribbon and in substantially parallel relation with the respective marginal pipe portions and individually extending into spaces between neighboring marginal pipe portions of a second ribbon and in substantially parallel relation with said last mentioned marginal pipe portions, and

a second tube conducting a heat absorbing fluid and having portions individually placed in spaces formed between neighboring marginal pipe portions of a third ribbon and in substantially parallel relation with the respective marginal pipe portions of said third ribbon individually extending into spaces between neighboring marginal pipe portions of said first ribbon and in substantially parallel relation with said last mentioned pipe portions.

7. A lining for the wall of a steam generator, comprising:

at least two heat absorbing ribbons, each ribbon being formed of a plurality of longitudinally juxtaposed pipes conducting a heat absorbing fluid,

each of said ribbons being bent 180 and having marginal pipes having spaced, parallel neighboring portions forming spaces therebetween, and

a continuous tube conducting a heat absorbing fluid and having portions individually placed in said spaces and extending alternately through a space formed by neighboring marginal pipe portions of a first ribbon and through a space formed by neighboring marginal pipe portions of the second ribbon.

8. A tubular lining for the walls of a steam generator,

comprising:

two tube systems,

each tube system comprising two tubular ribbons,

each tubular ribbon being formed of a plurality of longitudinally juxtaposed pipes,

each of said tubular ribbons being bent in meanderlike fashion and having marginal pipes having spaced, parallel, neighboring portions forming oblong spaces therebetween,

each tube system having at least one tube having poritons individually longitudinally placed in the oblong spaces formed between neighboring portions of the marginal pipes of a tubular ribbon of one of said tube systems and in the oblong spaces formed between neighboring portions of the marginal pipes of a tubular ribbon of the second tube system,

inlet means and outlet means connected to the pipes forming said tubular ribbons and to said tube of one of said tube systems for causing flow of heat absorbing fluid in parallel relation through the pipes and tube of said tube system from said inlet means to said outlet means, and

inlet means and outlet means connected to the pipes forming said tubular ribbons and to said tube of the second of said tube systems for causing flow of heat absorbing fluid in parallel relation through the pipes and tube of the second tube system from said inlet means to said outlet means.

9. A tubular lining as defined in claim 8 wherein each of said tube systems comprises at least one second tube having portions individually longitudinally placed in the 01310112 P C formed between neighboring portions of the marginal pipes of the tubular ribbons of the respective tube systems.

FOREIGN PATENTS 1,231,916 10/1960 France. 1,265,42 5 1 61 References Cited by the Examiner 53037; Q 3 UNITED STATES PATENTS 5 OTHER REFERENCES 6/1933 Ely 122 6 German printed application 1,098,006, Jan. 26, 1961 8/1933 Murry 122235 1 13 7 2/1939 Lucke 122-235 8/1961 Stahenow 122--51O X 10 FREDERICK L. MATTESON, JR., Primary Examiner. 4/ 1962 WitZke 122-235 ROBERT A. OLEARY, PERCY L. PATRICK, 4/1964 Davls 122510 

7. A LINING FOR THE WALL OF A STEAM GENERATOR, COMPRISING: AT LEAST TWO HEAT ABSORBING RIBBONS, EACH RIBBON BEING FORMED OF A PLURALITY OF LONGITUDINALLY JUXTAPOSED PIPES CONDUCTING A HEAT ABSORBING FLUID, EACH OF SAID RIBBONS BEING BENT 180* AND HAVING MARGINAL PIPES HAVING SPAFED, PARALLEL NEIGHBORING PORTIONS FORMING SPACES THEREBETWEEN, AND 